Highly Sensitive Ultraviolet and Visible Wavelength Sensor Composed of Two Identical Perovskite Nanofilm Photodetectors

Abstract This work reports the design of a wavelength sensor composed of two identical perovskite (FA 0.85 Cs 0.15 PbI 3 ) photodetectors (PDs) that are capable of discriminating incident wavelength in a quantitative way. Due to strong wavelength‐dependent absorption coefficient, the penetration depth of the photons in the FA 0.85 Cs 0.15 PbI 3 nanofilms increases with the increasing wavelength, leading to a gradual decrease of photo‐generated current for PD1, but an increase of photocurrent in PD2, according to the theoretical simulation of Technology Computer Aided Design. This special evolution of photo‐generated current as a function of wavelength facilitates the quantitative determination of the wavelength since the current ratio of both PDs monotonously decreases with the increase of wavelength from 265 to 810 nm. The average absolute error and the average relative error are estimated to be 7.6 nm and 1.68%, respectively, which are much better than other semiconductors materials‐based wavelength sensors previously reported. It is believed that the present perovskite film‐based wavelength sensor will have potential application in the future color/spectrum optoelectronic devices.